JP2005178929A - Registration device, and image forming device and image reading device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of limited productivity due to enlargement of a sheet-to-sheet interval for securing sufficient time for initializing action in such constitution as to correct skew of sheets by rotating rollers. <P>SOLUTION: Inclination of a sheet is detected, and a pair of resist rollers 2 are preliminarily inclined in accordance with detected inclination. The sheet is held in such a way that the tip of the sheet is parallel to the nip line of the resist rollers 2, and the resist rollers 2 are inclined to correct skew of the sheet. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a registration apparatus that corrects sheet inclination and misalignment applied to an image forming apparatus such as a copying machine, a printer, and a facsimile, or an image reading apparatus such as a scanner that reads a document image.

  Conventionally, in an apparatus that performs image formation and image reading, such as a copying machine, a printer, a facsimile machine, and a scanner, in order to adjust the posture and position of the sheet immediately before the image forming unit or the image reading unit, the skew correction of the sheet or the sheet Some use registration means which is means for correcting misalignment.

  Here, as these registration means, the leading edge of the sheet is abutted against the nip of the stopped roller pair, the sheet is bent, and the skew of the sheet is corrected by making the leading edge of the sheet follow the roller nip by the elasticity of the sheet. Then, a so-called loop registration method in which the roller pair is rotated at a predetermined timing to synchronize the sheet and the image has become the mainstream.

  However, in the above-described loop registration method, a loop space for forming a loop is necessarily required, and the apparatus is enlarged.

  In addition, when a sufficient loop space cannot be secured, there is a problem that jamming due to buckling occurs particularly with a thin paper that is weak.

  Further, there is a problem that a sound is generated when the sheet is brought into contact with the registration roller pair (so-called loop sound), and the skew correction ability is changed depending on the strength of the sheet. Specifically, with thin paper that does not scratch the sheet, the contact pressure when the sheet tip contacts the registration roller nip is insufficient, and the sheet tip may not fully contact the registration roller pair. I can't. In addition, for thick paper with strong sheet stiffness, there is a problem that the nip of the registration roller pair penetrates due to the impact applied to the nip of the registration roller. To prevent this, a load (brake member) is applied to the registration roller pair. There are cases where it is possible to cope with the situation, which increases the product cost.

  In addition, when the leading edge of the sheet is curled or bent, the leading edge of the sheet does not accurately follow the nip portion of the pair of registration rollers, and the skew correction cannot be performed accurately, and the printing accuracy is sufficiently satisfied. It was not a thing.

  Further, in recent years, as image forming apparatuses and image reading apparatuses are digitized, the interval between sheets (between sheets) is reduced, and by processing many sheets in a short time, for example, in the case of image formation, A substantial increase in image forming speed has been achieved without increasing the image forming process speed.

  On the other hand, in a conventional analog apparatus, for example, a copying machine, an optical device for exposing a document reciprocates for the number of copies even when a single sheet (document) is read and then continuously copied. Therefore, the interval between sheets (between sheets) was inevitably determined.

  However, since the reading of the original and the image formation thereof are digitized, the image information can be electrically encoded and stored in the memory after the original is read once. During image formation, the information in the memory is read out and an image corresponding to the image information of the document is formed on the photosensitive member by an exposure device such as a laser beam or an LED array. No mechanical movement is required.

  However, in the loop registration method described above, the sheet has to be temporarily stopped in order to form a loop, and the interval between sheets (between sheets) is inevitably determined, and the substantial image forming speed is determined. It greatly hindered improvement of (productivity).

  In order to overcome the above problems, a registration apparatus has been proposed that can automatically correct the inclination of the sheet due to the skew of the sheet. That is, in this apparatus, a pair of conveyance rollers (registration rollers) that nipping and conveying the sheet, a sensor provided on the downstream side in the conveyance direction of the conveyance roller, and a sensor for detecting the amount of inclination of the sheet, The image forming apparatus includes a conveyance roller inclination correction unit that displaces the registration roller in a direction orthogonal to the sheet conveyance direction, and displaces the conveyance roller in accordance with the sheet inclination based on information of the sheet inclination amount detection sensor. Thus, the skew of the sheet is corrected.

However, in this registration apparatus, when the skew correction of the sheet is performed as described above, the conveyance roller (registration roller) is inclined with respect to the original sheet conveyance direction. When the sheet is conveyed, the sheet is conveyed in an oblique direction with respect to the original sheet conveying direction (so-called skew feeding). For example, when it is applied to an image forming apparatus, there is a problem that an image is shifted and transferred with respect to a sheet by oblique feeding in a direction perpendicular to the sheet conveying direction, and the printing accuracy is remarkably deteriorated. For this problem, a sensor for detecting the lateral registration position in the direction orthogonal to the sheet conveyance direction at the side edge of the sheet is arranged downstream of the conveyance roller, and the pair of conveyance rollers is set according to the detection result of the lateral registration position detection hand sensor. Is moved in a direction orthogonal to the sheet conveyance direction to perform position correction (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 10-067448

  However, the sheet is provided with an inclination correction mechanism that displaces the conveyance roller so as to be inclined with respect to a direction orthogonal to the sheet conveyance direction, and a lateral registration position correction mechanism that moves the conveyance roller in a direction orthogonal to the sheet conveyance direction. When the sheet is continuously conveyed, the inclination correction mechanism and the lateral registration position correction mechanism are provided for the skew correction of the subsequent sheet after the trailing edge of the preceding sheet has passed through the nip of the conveyance roller. It is necessary to initialize and return the inclination of the conveying roller and the lateral registration position to the initial position. Therefore, it is necessary to sufficiently widen the conveyance interval between successive sheets to ensure a sufficient time for the initialization operation. For this reason, there is a problem that the gap between the sheets is widened, and the substantial image forming speed (productivity) is not increased.

  The present invention has been made in view of the above circumstances, overcomes the above-described problems, reduces the sheet-to-sheet spacing (inter-sheet space) to the limit, improves printing accuracy, and increases the productivity of the image forming apparatus or the image reading apparatus. It is an object to provide a registration apparatus capable of doing things.

  The present invention is a registration apparatus that feeds a sheet at a timing, a first conveying unit that conveys the sheet, a second conveying unit that is arranged downstream of the first conveying unit in the sheet conveying direction, Based on the detection information obtained by the sheet state detection means for detecting at least one of the inclination and position of the conveyed sheet, and at least the inclination and position of the sheet by moving the first conveyance means. A conveying means state correcting means for correcting one of the conveying means, and a conveying force releasing means for releasing the conveying force for conveying the sheet of the first conveying means, and the conveying force when the sheet reaches the second conveying means. The releasing means releases the conveying force of the first conveying means, and the conveying means state correcting means moves the first conveying means.

  As described above, the registration apparatus according to the present invention detects the inclination of the sheet and the position of the side edge, and only performs a simple operation of tilting the registration roller in a direction perpendicular to the sheet conveyance direction to correct skew feeding and lateral movement. Since the registration position is corrected, the sheet conveyance speed can be increased and the speed can be increased. In addition, unlike the conventional loop registration method, the sheet is not temporarily stopped at the registration roller portion to form a loop, so that a paper gap can be minimized and a highly productive apparatus can be obtained. Not only can it be provided, there is no generation of loop noise, and the problem of buckling when forming a thin paper loop can be solved. Naturally, a loop forming space is not required, and since the correction mechanism is simple, the apparatus can be downsized and provided at low cost. Further, the skew and lateral misregistration of the sheet S can be accurately corrected without being affected by the curl or the like of the leading end of the sheet S.

(First embodiment of the invention)
Detailed description will be given below with reference to the drawings. FIG. 1 is a cross-sectional view of a printer as an image forming apparatus to which a registration apparatus according to an embodiment of the present invention is applied. In FIG. 1, 1000 is a printer, and in the figure, 120 is a controller as a control means for controlling the printer, 100 is an upper cassette, and a pickup roller in which the sheets in the cassette 100 are moved up and down / rotated at a predetermined timing 101, the feed roller 102 and the retard roller 103 are separated and fed one by one. Then, the sheet fed from the sheet feeding section passes through the conveyance path 108 constituted by the guide plates 106 and 107 by the conveyance roller 105, is delivered to the conveyance path 110 constituted by the guides 109 and 111, and the pre-registration roller pair 130 And is guided to the registration roller unit 1 having the registration roller pair 2. After correcting the skew of the sheet by the registration roller unit 1, the sheet is conveyed to the transfer unit 112b.

  The skew correction operation in the registration roller unit will be described in detail later.

  A photosensitive drum 112 rotates in the clockwise direction in the figure. Reference numeral 111 denotes a laser modulation (laser scanner) which is an image forming means. The laser beam is folded back by a mirror 113 and irradiated to an exposure position 112a on the drum to form a latent image on the drum. As visualized. Reference numeral 115 denotes a transfer charger for transferring the toner image on the drum to the sheet. Reference numeral 116 denotes a separation charger for electrostatically separating the drum and the sheet, and constitutes an image forming unit. Reference numeral 112b denotes a transfer portion, and the toner image on the photosensitive drum 112 is transferred onto the sheet S at this position.

  The leading edge of the sheet S that has passed through the registration roller pair 2 is detected by the exposure start sensor 131, and laser light irradiation by the laser modulation 111 is started.

Note that the distance l ₁ from the exposure start sensor 131 to the transfer portion 112b is disposed at a position equal to the distance l ₀ from the laser light irradiation position 112a to the transfer portion 112b of the photosensitive drum 112. It is possible to synchronize the tip position of the image on the drum 112.

  Reference numeral 117 denotes a conveyance belt that conveys an image-formed sheet material, 118 denotes a fixing device, and 119 denotes a paper discharge roller. The sheet material on which the image is formed is discharged by a discharge roller 119.

  2000 is a scanner, 201 is a scanning optical system light source, 202 is a platen glass, 203 is an original platen that opens and closes, 204 is a lens, 205 is a light receiving element (photoelectric conversion), 206 is an image processing unit, and 208 is an image processing unit It is a memory part for memorize | storing the image processing signal processed by.

  An original image read by the scanning optical source 201 is processed by an image processing unit 206, electrically encoded, converted into an electric signal 207, and transmitted to a laser modulation 111 serving as an image forming unit. Further, the image information processed and encoded by the image processing unit is temporarily stored in the memory 208, and can be transmitted to the laser modulation 111 as needed by a signal from the controller 120. ing.

  Here, 1000 is a printer, and 2000 is a scanner. However, the printer 1000 and the scanner 2000 may be integrated as shown in FIG.

  The printer 1000 can function as a copier when the image forming unit processing signal is input to the laser modulation 111, whether it is a separate unit or as an integral unit, and functions as a FAX when a FAX transmission signal is input, and receives a PC output signal. Then, it functions as a printer. Conversely, if the processing signal of the image processing unit 206 is transmitted to another FAX, it functions as a FAX. Here, instead of the pressure plate 203, if an automatic document feeder 250 as shown by a two-dot chain line is attached, the document is automatically read.

  Next, the details of the registration roller portion will be described with reference to FIGS.

  FIG. 2 shows a registration apparatus according to an embodiment of the present invention, FIG. 2 is a side view thereof, FIG. 3 is a plan view thereof, and FIG. 4 is a block diagram thereof.

  2 and 3, the registration roller pair 2 is rotatably supported by bearings 11 and 12 fixed to the side plates by a front side plate 10a and a rear side plate 10b of the frame 10, respectively. Further, as shown in FIG. 3, skew detection sensors 3a and 3b for detecting the inclination of the leading edge of the sheet S are arranged in a direction orthogonal to the sheet conveying direction on the upstream side of the registration roller pair 2 in the conveying direction. Arranged at intervals L.

  The center line 3c connecting the skew detection sensors 3a and 3b is arranged to be parallel to the axis 112c of the photosensitive drum 112 provided on the downstream side in the transport direction.

  2 and 3, the frame 10 is attached so as to be rotatable about a rotation shaft 14 provided on a stay 13 fixed to the front plate 1001 and the rear plate 1002 of the apparatus main body 1000. I'm. The rotation shaft 14 becomes the center of the rotational movement when the registration roller pair 2 described later is tilted and becomes the reference position on the axis of the registration roller pair 2.

  The registration roller 2a is pressed against the registration roller 2b by a pressure spring (not shown). Further, gears 15 and 16 are attached to one side of the registration roller pair 2a and 2b, respectively, so that the registration roller pair 2a and 2b rotate in synchronization with each other.

  Further, a drive input gear 27 is fixed to the shaft end of the registration roller 2b, and meshes with a gear 28 fixed to the output shaft of the registration motor 17, so that the registration roller 17 is driven by the registration motor 17. 2 rotations are possible.

  A gear 22 is fixed to the front side of the frame 10 and meshes with a rack gear 23 fixed to the output shaft of the turning motor 24 attached to the stay 13.

  For example, when the pinion gear 23 rotates in the clockwise direction in FIG. 3 due to the action of the turning motor 24, the frame 10 and the registration roller pair 2 provided on the frame 10, the registration motor 17, etc. All the members attached to are configured to be able to rotate counterclockwise about the rotation shaft 14. That is, by the action of the turning motor 24, the registration roller pair 2 can be displaced (turning movement operation) so as to be inclined with respect to the direction orthogonal to the sheet S conveyance direction P. In addition, a home position sensor 25 is provided on the stay 13 so that the home position position of the registration roller pair 2 can be detected.

  Here, the home position position of the registration roller pair 2 is determined such that the nip line thereof is parallel to the rotation center axis 112c of the photosensitive drum 112. Further, the nip of the registration roller pair 2 can be released by ON / OFF control of a registration release solenoid 50 (not shown).

  FIG. 4 is a block diagram showing a control system for controlling the operation of the image forming apparatus. As shown in the block diagram, each of the roller pairs 102, 105, and 130 described above receives a driving force from the main motor M, and receives signals from the controller 120 via the respective driving circuits 102a, 105a, and 130a, and the clutches 102b, 105b, and 130b, Is configured to perform ON / OFF control. Further, the photosensitive drum 112, the conveyance belt 117, the fixing device 118, and the paper discharge roller 119 are directly connected to the main motor M, and can rotate in synchronization with the main motor M, respectively.

  Further, the size of the sheets loaded in the sheet feeding cassettes 100 and 100 ′ is detected by sheet size detection sensors 100b and 100b ′ (not shown), and the information is connected to the controller 120.

  The skew detection sensors 3a and 3b described above are connected to the controller 120, and detection signals obtained by the sensors 3a and 3b are respectively input thereto. In the controller 120, the amount of inclination of the sheet S is calculated by the calculation circuit 160 based on the detection signal of each sensor. The controller 120 is connected to the drive circuits 17a and 24a of the registration motor 17 and the swing motor 24, respectively, and outputs necessary control signals based on the detection results to drive the motors 17 and 24 by a predetermined amount. It has become. Also, a registration release solenoid 50 driving circuit 50a for releasing the nip of the registration roller pair 2 is connected to the controller 120 and outputs a necessary control signal to control ON / OFF of each registration release solenoid 20. It is like that.

  Next, the operation of this registration apparatus will be described with reference to FIGS. Since the description of the operation of the entire image forming apparatus is different from the essence of the present invention, the description is omitted and only the registration unit is described.

First, when a start button (not shown) of the image forming apparatus is pressed, the turning motor 24 is operated, and the home position sensor 25 initializes the registration roller pair 2 in the turning direction. (Step S1) Then, the registration motor 17 is driven and the registration roller pair 2 starts to rotate. (Step S2) with respect to the registration roller pair 2 to the rotation, as shown in FIG. 6 (a), the sheet conveying direction P _1, the sheet S ₁ was theta ₁ skew at the conveying speed V ₁ is transmitted, FIG. 6 As shown in (b), when the sheet is moved along the sheet conveyance direction P ₁ and moves forward, the skew detection sensors 3a and 3b arranged on the upstream side of the registration roller pair 2 pass the leading edge of the sheet S _1. Is detected (step S3). Inclination detecting sensor 3a, a detection signal b and the sheet edge position detecting sensor 4, by being input to the controller 120, the inclination theta ₁ of the sheet S ₁ is calculated (step S4). As shown in FIG. 6E, the amount of sheet inclination is calculated from the difference in sheet detection time between the skew detection sensors 3a and 3b. When the detection timings of the skew detection sensors 3a and 3b are detected with a time difference of Δt, the sheet inclination amount θ ₁ is the sheet S ₁ conveyance speed V ₁ and the skew detection sensors 3a and 3b pitch. Assuming that (inter-sensor distance) is L, it can be calculated by the following calculation formula as is apparent from FIG.
θ ₁ = tan ⁻¹ (Δt × V ₁ / L) (Formula 1)
Then, the controller 120 determines whether or not there is an inclination deviation detected by the skew detection sensors 3a and 3b (step S5), and particularly corrects when there is no inclination deviation (when θ = 0). If no operation is performed but there is a tilt deviation, a correction amount for the tilt (that is, the drive amount θ ₁ of the turning motor 24) is calculated (step S6).

Therefore, as shown in FIG. 6 (c), the turning motor 24 is driven by a predetermined amount in accordance with the correction amount related to the tilt deviation, and the registration roller pair 2 is preliminarily set in the direction of the arrow F in the direction of arrow F _{1 by} θ _1. A tilting operation is performed (steps S7 and S8). Further, when the conveyed sheet is the first sheet is, theta ₁ skewed sheets S ₁ is the sheet transport direction P _1, fed at a conveying speed V _1, previously theta ₁ inclined to the nip portion of the registration roller pair 2 It enters and is pinched (step S12). Roller pair 2 sheets being sandwiched by S _1, as shown in FIG. 6 (d), with respect to the inclination of the sheet S _1, the turning motor 24 drives the sheet S ₁ held between the pair of registration rollers 2 The registration roller pair 2 is rotated about the rotation shaft 14 in the direction of arrow G by θ ₁ until the tip of the roller is parallel to the axial direction of the transfer portion 112b (axial direction of the photosensitive drum of the transfer portion). skew of the sheet S ₁ is being corrected by the operation (step S13 and S14).

By a series of these operations, the inclination of the sheet is detected, and according to the amount of inclination, the registration roller pair 2 is inclined in advance, and the sheet is sandwiched so that the front end of the sheet and the nip line of the registration roller pair 2 are parallel, By correcting the skew feeding of the sheet by tilting the registration roller pair 2, skew feeding correction can also be performed. By above correction operation is performed, the sheet S ₁ is inclined with respect to the transfer portion 112b and lateral registration misalignment is sent out with no a precise conveying posture is printed. Then, if there is no subsequent sheet is, (Step 16) When the sheet S ₁ trailing end leaves the registration roller pair 2, (Step 17) performs a registration roller pair 2 of the initializing operation, (Step 18) skew of the next sheet And prepare for skew feeding correction. This initialization operation is performed by the home position sensor 25 as described above.

Next, description will be given with reference to FIGS. 7A to 7D when there is a subsequent sheet. As shown in FIG. 7 (a), when the leading edge of the preceding sheet S ₁ is conveyed to the transfer section 112b (step S15), and the pair of registration rollers 2 nip is released by registration release solenoid 50 (step S22) . Then, before the trailing edge of the sheet S ₁ which precedes provided to a subsequent skew and skew correction of the sheet S ₂ moves away the nip portion of the registration roller pair 2, performs the initialization operation registration roller pair 2 (Step 23) . Next, as shown in FIG. 7B, the skew detection in which the subsequent sheet S ₂ skewed by θ ₂ at the sheet transport direction P ₁ and the transport speed V ₁ is arranged on the upstream side of the registration roller pair 2 is detected. sensor 3a, b passing through time of the sheet S ₂ tip is detected by the detection signal by being input to the controller 120, the inclination of the sheet S theta ₂ is calculated (step S3, 4). Then, the controller 120 determines whether or not there is an inclination deviation detected by the skew detection sensors 3a and 3b (step S5), and particularly corrects when there is no inclination deviation (when θ = 0). If no operation is performed, but there is a tilt deviation, a correction amount for the tilt (that is, the drive amount θ ₂ of the turning motor 24) is calculated (step S6). Therefore, as shown in FIG. 7C, before the trailing edge of the preceding sheet S ₁ passes through the nip portion of the registration roller pair 2, the turning motor 24 is moved by a predetermined amount according to the correction amount related to the tilt deviation. Then, the registration roller pair 2 is tilted by θ _{2 in the} direction of arrow F about the rotation shaft 14 (steps S7 and S8). When the conveyed sheet is the second or later, after the trailing edge of the preceding sheet S ₁ passes through the nip of the registration roller pair 2, the nip of the registration roller pair 2 is pressurized by the registration release solenoid 50 (step S11). . If the leading edge of the sheet S ₂ has already reached the nip part of the registration roller pair 2 or if it has not reached, after the leading edge of the sheet S ₂ has entered the nip part of the registration roller pair 2 and is nipped , as shown in (step S12) FIG. 7 (d), the relative inclination of the sheet S _2, the turning motor 24 is driven, the registration roller pair 2 on the sandwiched sheet S ₂ tip of the transfer portion 112b shaft The registration roller pair 2 is rotated about the rotation shaft 14 in the direction of arrow G by θ ₂ until it is parallel to the direction (axial direction of the photosensitive drum of the transfer portion), and this operation causes the sheet S ₂ to skew. Is corrected (steps S13 and S14).

  Thus, even when the conveyance interval between the sheets is short, by releasing the nip of the registration roller pair, before the trailing edge of the preceding sheet in preparation for the subsequent sheet passes through the nip of the registration roller pair 2, The registration roller pair 2 is initialized in preparation for the skew correction of the subsequent sheet, the inclination of the subsequent sheet is detected, and the registration roller pair 2 is inclined in advance according to the inclination amount, and the leading edge of the sheet and the registration roller pair 2 are detected. The registration roller pair nip is pressed to hold the sheet, the registration roller pair 2 is tilted to correct the skew of the sheet, and the skew correction can be performed simultaneously with the skew correction. Become. Thereafter, the above-described operation is repeated to enable continuous paper feeding.

  By executing the correction operation described above, in continuous conveyance of a sheet having a short sheet-to-sheet conveyance interval, the sheet is fed and printed with an accurate conveyance posture with no inclination with respect to the transfer unit 112b. These operations make it possible to reduce the gap between sheets to the maximum (substantially between the sheets) while performing highly accurate skew correction and skew feeding correction without stopping the sheet. It became possible to improve the formation speed (productivity).

  Note that such a registration apparatus is limited to an image forming apparatus as long as the sheet is not inclined with respect to a subsequent process (the transfer unit 112b in the case of an image forming apparatus) and needs to be sent out accurately. However, the present invention can be applied to any apparatus such as an image reading apparatus.

(Second Embodiment of the Invention)
Next, a second embodiment of the present invention will be described with reference to FIGS.

  Note that the description of the entire image forming apparatus and the parts having the same reference numerals are the same as those in the first embodiment, and thus the description thereof is omitted. Further, since the turning operation of the registration roller pair 2 by the turning motor 24 is the same as that in the first embodiment, the description thereof is omitted.

  8 to 9 show a registration apparatus according to the present embodiment. FIG. 8 is a side view thereof, FIG. 9 is a plan view thereof, FIG. 10 is a block diagram, FIG. 11 is a flowchart, FIG. 13 is an operation explanatory diagram.

  8 and 9, on the downstream side of the registration roller pair 2 in the conveyance direction, as shown in FIG. 8, skew detection sensors 3a and 3b for detecting the inclination of the leading edge of the sheet S are orthogonal to the sheet conveyance direction. A sheet edge position detection sensor 4 including a CCD sensor or the like is disposed at a predetermined interval L in the direction in which the sheet is to be moved. The center line 3c connecting the skew detection sensors 3a and 3b is arranged to be parallel to the axis 112c of the photosensitive drum 112 provided on the downstream side in the transport direction.

  On the back side of the registration roller pair 2, a connecting member 18 for connecting the registration rollers 2a and 2b is provided. The connecting member 18 is rotatably supported by the respective registration rollers 2a and 2b, but is regulated in the longitudinal direction of the registration roller pair 2. When the connecting member 18 moves in the thrust direction, the connecting member 18 is synchronized therewith. Thus, the registration roller pair 2 is also configured to move in the thrust direction. The connecting member 18 is provided with a rack gear portion 18b, and is configured to mesh with a pinion gear 19 fixed to the output shaft of the lateral registration motor 20. That is, for example, when the pinion gear 19 rotates in the clockwise direction in FIG. 8, the registration roller pair 2 is configured to move in the right direction in FIG. That is, by driving the lateral registration motor 20, the registration roller pair 2 can be moved in a direction (thrust movement operation) perpendicular to the sheet conveyance direction P. The home position sensor 21 is configured to detect the home position of the registration roller pair 2.

  FIG. 10 is a block diagram showing a control system for controlling the operation of the image forming apparatus. The skew detection sensors 3a and 3b and the sheet edge position detection sensor 4 described above are connected to a controller 120, and each of the sensors. The detection signals obtained at 3a, 3b, and 4 are respectively input. In the controller 120, the arithmetic circuit 160 calculates the amount of inclination and the amount of positional deviation of the sheet S based on the detection signal of each sensor. The controller 120 is connected to a drive circuit 20a of the lateral registration motor 20, and outputs a necessary control signal based on the detection result to drive each motor 20 by a predetermined amount.

  Next, the operation of this registration apparatus will be described with reference to FIGS.

First, when a start button (not shown) of the image forming apparatus is pressed, the lateral registration motor 20 and the turning motor 24 are operated, and the home position sensors 21 and 25 perform the initialization operation of the registration roller pair 2. (Step S1) Then, the registration motor 17 is driven and the registration roller pair 2 starts to rotate. (Step S2) When the sheet S ₁ skewed by θ ₁ from the sheet conveying direction P is sent to the rotating registration roller pair 2 as shown in FIG. _First , the sheet S ₁ enters the nip portion of the registration roller pair 2 and is nipped. As shown in FIG. 12B, the sheet S ₁ sandwiched between the registration roller pair 2 is fed along the sheet conveyance direction P and advanced to move the skew S disposed on the downstream side of the registration roller pair 2. line detection sensor 3a, lateral displacement by the sheet edge position detecting sensor 4 with passage time of the sheet S ₁ tip is detected by b is detected. (Step S6).

Skew detection sensors 3a, b and the detection signal of the sheet edge position detecting sensor 4, by being input to the controller 120, lateral displacement of the slope and the sheet sheet S ₁ held between the registration roller pair 2 is calculated (Step S7). That is, the amount of sheet inclination is calculated from the difference between the sheet detection times of the skew detection sensors 3a and 3b, and the lateral registration deviation is directly detected by the sheet edge position detection sensor 4 composed of a CCD sensor or the like. Is done. Then, the controller 120 determines whether or not there is a tilt deviation detected by the skew detection sensors 3a and 3b (step S8), and if there is no deviation in the tilt (when θ = 0), the controller 120 It is determined whether or not there is a lateral registration misalignment (Step 22). Here, when there is no lateral registration deviation, no correction operation is performed, but when there is a lateral registration deviation, the lateral registration motor 20 is driven until the lateral registration position is corrected to a correct position. Whether or not the lateral misregistration has been corrected is determined by the detection signal of the sheet edge position detection sensor 4 (Steps 23, 24, and 25).

If skew of the sheet S ₁ is detected in Step 8, the skew correction amount θ ₁ is calculated (Step 9), and the turning motor 24 is driven until the registration roller pair 2 turns by θ ₁ (Step 10). , 11).

Note that the calculation methods of the output values of the skew detection sensors 3a and 3b and the inclination correction amount θ ₁ are the same as those in (Equation 1) in the first embodiment, and thus the description thereof is omitted.

At this time, as shown in FIG. 12D, the leading edge of the sheet S sandwiched between the registration roller pair 2 is parallel to the axial direction of the transfer portion 112b (the axial direction of the photosensitive drum of the transfer portion), Next, it is determined whether or not there is a lateral registration shift (Step 12). If there is a lateral registration shift, the registration roller pair 2 is controlled to move in the direction perpendicular to the sheet S ₁ conveyance direction (H direction in FIG. 12d), and the lateral registration motor 20 is driven until the lateral registration position is corrected to the correct position. To do. Whether or not the lateral misregistration has been corrected is determined by a detection signal of the sheet edge position detection sensor 4. (Steps 13, 14, 15) Although the lateral registration of the sheet S ₁ is also in an appropriate position, the registration roller pair 2 is rotated by θ ₁ by the turning motor 24, so the conveyance direction P of the sheet S ₁ Is inclined by θ ₁ minute. As a result, the entire sheet S ₁ becomes in its inclined angle in the conveying in oblique direction (hereinafter oblique feed referred to) by the possible (see chain line in FIG. 12d).

Therefore, after the registration roller pair 2 is rotated by θ ₁ , the lateral registration motor 20 is driven to control the movement of the registration roller pair 2 in the direction perpendicular to the sheet S ₁ conveyance direction (G direction in FIG. 12e). Thus, the skew feeding of the sheet S is corrected, and the sheet S is conveyed as shown by the broken line in FIG. Since in the example described above the sheet S is fed obliquely in an inclined state theta ₁ minute with respect to the transfer portion 112b, thrust direction movement velocity V ₂ of the pair of registration rollers 2 by the lateral moving motor 20, as shown in FIG. 12f
V ₂ = V ₁ × tanθ ₁ … (Formula 2)
And can be driven in the G direction in FIG. 6 at the speed of V ₂ described above. (Step S16, 17)
As a result, the sheet S can be subjected to skew correction and skew feeding correction.

And if there is no subsequent sheet, the sheet S ₁ trailing edge Once passed through the registration roller pair 2, stops (Step 19) lateral moving motor 20 (Step 20). By above correction operation is performed, the sheet S ₁ is printed is fed with a precise conveying posture without inclination with respect to the transfer unit 112b. Thereafter, the registration roller pair 2 is initialized, and (Step 21) prepares for the skew feeding and skew feeding correction of the next sheet S. This initialization operation is performed by the home position sensors 21 and 25 as described above.

Next, a description will be given of the case where there is a subsequent sheet with reference to FIGS. As shown in FIG. 13A, when the leading edge of the preceding sheet S ₁ is conveyed to the transfer section 112b (step S27), the nip of the registration roller pair 2 is released by the registration release solenoid 50, and the lateral registration motor 20 is moved. Stop (step S28). Then, as shown in FIG. 13B, before the trailing end of the preceding sheet S ₁ passes through the nip portion of the registration roller pair 2 in preparation for skew feeding and skew feeding correction of the subsequent sheet S ₂ , the registration roller The pair 2 initialization operation is performed (Step 30). Next, as shown in FIG. 13C, the sheet S ₂ skewed by θ ₂ from the sheet conveying direction P ₁ is sent to the registration roller pair 2 and the conveyed sheet is the second and subsequent sheets. the rear end of the preceding sheet S ₁ is passed through the nip of the registration roller pair 2, the registration release solenoid 50 to pressurize the nip of the registration roller pair 2 (step S4, 5). When the leading edge of the sheet S ₂ has already reached the nip portion of the registration roller pair 2 or has not reached, the leading edge of the sheet S ₂ enters the nip portion of the registration roller pair 2 and is pinched. 13 (d), the by advancing sent along the sheet conveying direction P, the registration roller pair 2 on the downstream side arranged skew detection sensors 3a, passing time of the sheet S ₂ tip by b Is detected, and a lateral registration shift is detected by the sheet edge position detection sensor 4. (Step S6).

Skew detection sensors 3a, b and the detection signal of the sheet edge position detecting sensor 4, by being input to the controller 120, lateral displacement of the slope and the sheet sheet S ₁ held between the registration roller pair 2 is calculated (Step S7). Then, the controller 120 determines whether or not there is a tilt deviation detected by the skew detection sensors 3a and 3b (step S8), and if there is no deviation in the tilt (when θ = 0), the controller 120 It is determined whether or not there is a lateral registration misalignment (Step 22). Here, when there is no lateral registration deviation, no correction operation is performed, but when there is a lateral registration deviation, lateral registration correction is performed (Steps 23, 24, and 25).

If skew of the sheet S ₂ is detected in Step 8, the skew correction amount θ ₂ is calculated (Step 9), and the turning motor 24 is driven until the registration roller pair 2 turns by θ ₂ . (Steps 10 and 11) At this time, as shown in FIG. 13D, the leading edge of the sheet S _{2 held} between the registration roller pair 2 is in the axial direction of the transfer portion 112b (the axial direction of the photosensitive drum of the transfer portion). Next, it is determined whether or not there is a lateral misalignment (Step 12). If there is a lateral registration shift, the registration roller pair 2 is controlled to move in a direction perpendicular to the sheet S ₁ conveyance direction (H direction in FIG. 13e), and the lateral registration motor 20 is driven until the lateral registration position is corrected to the correct position. To do. (Step13,14,15) Also, since the registration roller pair 2 is rotated moving theta ₂ minutes by the turning motor 24 to drive the lateral moving motor 20, the conveying direction perpendicular to the direction of the resist roller pair 2 sheet S ₂ by moving control in the (G direction in FIG. 13e), to correct the feed oblique sheet S _2, for conveying the sheet S ₂ as shown in broken line in FIG. 13e. In the above-described example, the sheet S ₂ is obliquely fed while being inclined by θ _{2 with} respect to the transfer portion 112b. Therefore, the thrust direction moving speed V ₃ of the registration roller pair 2 by the lateral registration motor 20 is as shown in FIG. Figure 13 (e) may be driven in the middle direction G by the calculation can speed of the V ₃ to. (Steps S16, 17) Thereby, the sheet S can be subjected to skew feeding correction and skew feeding correction.

  Thus, even when the conveyance interval between the sheets is short, by releasing the nip of the registration roller pair, before the trailing edge of the preceding sheet in preparation for the subsequent sheet passes through the nip of the registration roller pair 2, In preparation for the skew and lateral registration correction of the subsequent sheet, the initialization operation of the registration roller pair 2 is performed, the nip of the registration roller 2 pair is pressed to sandwich the subsequent sheet, and the skew correction and lateral registration correction of the sheet are performed. At the same time, skew feeding correction can be performed. Thereafter, the above-described operation is repeated to enable continuous paper feeding.

  By executing the correction operation described above, in continuous conveyance of a sheet with a short sheet-to-sheet conveyance interval, the sheet is fed and printed with an accurate conveyance posture with no inclination or lateral registration position deviation with respect to the transfer unit 112b. . These operations reduce the sheet-to-sheet spacing (between sheets) to the utmost while performing highly accurate skew correction, lateral registration position correction, and skew feeding correction without temporarily stopping the sheet. As a result, the substantial image forming speed (productivity) can be improved.

  As in the first embodiment, such a registration apparatus is an apparatus that is capable of accurately feeding the sheet S to the subsequent process (the transfer unit 112b in the case of an image forming apparatus) without an inclination. The present invention is not limited to the forming apparatus, and can be applied to any apparatus such as an image reading apparatus. In this embodiment, the inclination and the lateral registration position are detected and the inclination and the lateral registration position are corrected simultaneously. However, at least one of the inclination and the lateral registration position is detected, and the inclination and the lateral registration position are corrected. It goes without saying that at least one of the corrections can be performed.

(Third embodiment of the invention)
Next, a third embodiment of the present invention will be described with reference to FIG.

  Note that the description of the entire image forming apparatus and parts having the same reference numerals are the same as those in the first and second embodiments, and thus the description thereof is omitted. Further, since the turning operation of the registration roller pair 2 is the same as in the first and second embodiments, the description thereof is omitted.

  Further, since the difference from the first and second embodiments is only the sheet skew amount detection method, the description using a flowchart and a block diagram will be omitted.

  FIG. 14 shows a plan view of a registration apparatus according to the third embodiment of the present invention. In the figure, a sheet edge position detection sensor 4 constituted by a CCD sensor or the like is disposed downstream of the registration roller pair 2 in the conveyance direction.

  A sheet S skewed by θ from the sheet conveying direction P is sent. As shown in FIG. 14A, the sheet S sandwiched between the registration roller pair 2 is fed along the sheet conveying direction P and advanced to detect the position of the sheet end located on the upstream side of the registration roller pair 2. The sensor 4 detects the passage time of the leading edge of the sheet S, and the sheet edge position detection sensor 4 detects a displacement in the thrust direction.

Then, as shown in FIG. 14b, reads the value of the predetermined time t ₁ for the second time again after the sheet edge position detection sensor 4. Assuming that the difference between the values obtained by the first and second sheet edge position detection sensors 4 is ΔL and the sheet conveyance speed is V ₁ , the sheet inclination amount θ is θ = tan ⁻¹ as is apparent from FIG. 14c. (ΔL / (V ₁ × t ₁ )) (Formula 6)
It can be calculated with. As a result, since both the sheet inclination amount θ and the sheet S positional deviation amount can be detected only by the sheet edge detection sensor 4, if the same control as in the first and second embodiments is performed, the skew correction and the lateral registration are controlled. Correction is possible.

  By the above-described method, it is possible to detect both the sheet skew amount and the sheet thrust position deviation only by the sheet edge detection sensor 4, and with a very simple configuration, the skew correction and lateral registration can be performed with high accuracy. Correction and skew feed correction can be performed.

1 is a schematic cross-sectional view of an image forming apparatus to which an embodiment of the present invention is applied. The side view of the resist part to which embodiment of this invention is applied. The top view of the resist part to which embodiment of this invention is applied. 1 is a block diagram of an image forming apparatus to which an embodiment of the present invention is applied. The flowchart which applied embodiment of this invention. Operation | movement explanatory drawing of the resist part to which embodiment of this invention is applied. Operation | movement explanatory drawing of the resist part to which embodiment of this invention is applied. The side view of the resist part to which 2nd Embodiment of this invention is applied. The top view of the resist part to which 2nd Embodiment of this invention is applied. The block diagram of the image forming apparatus to which 2nd Embodiment of this invention is applied. The flowchart which applied 2nd Embodiment of this invention. Operation | movement explanatory drawing of the resist part to which 2nd Embodiment of this invention is applied. Operation | movement explanatory drawing of the resist part to which 2nd Embodiment of this invention is applied. Operation | movement explanatory drawing of the resist part of 3rd Embodiment.

Explanation of symbols

1 Registration unit
2 Registration roller
3 Skew detection sensor
4 Paper edge position detection sensor
17 Registration motor
20 Lateral registration motor
24 slewing motor
131 Exposure start sensor
111 Laser modulation (laser scanner)
112 Photosensitive drum
120 controller
1000 printer
2000 scanner

Claims (5)

A registration device that takes out the timing of a sheet and sends it out.
First conveying means for conveying a sheet;
A second conveying means disposed downstream of the first conveying means in the sheet conveying direction;
Sheet state detection means for detecting at least one of the tilt and position of the conveyed sheet;
A conveying unit state correcting unit that corrects at least one of the inclination and the position of the sheet by moving the first conveying unit based on the detection information obtained by the sheet state position detecting unit;
A conveyance force releasing means for releasing the conveyance force for conveying the sheet of the first conveyance means,
When the sheet reaches the second conveyance unit, the conveyance force of the first conveyance unit is released by the conveyance force release unit, and the first conveyance unit is moved by the conveyance unit state correction unit. apparatus. A registration device that takes out the timing of a sheet and sends it out.
First conveying means for conveying a sheet;
A second conveying means disposed downstream of the first conveying means in the sheet conveying direction;
Sheet inclination detecting means for detecting the inclination of the conveyed sheet;
A conveying means inclination correcting means for displacing the first conveying means so as to incline in a direction orthogonal to the sheet conveying direction based on the detection information obtained by the sheet inclination detecting means;
A conveying force releasing means for releasing the conveying force for conveying the sheet of the first conveying means,
A registration apparatus, wherein the conveying force of the first conveying means is released by the conveying force releasing means, and the first conveying means is tilted by the conveying means inclination correcting means.   The conveying force of the first conveying unit is canceled by the conveying force releasing unit, and the first conveying unit is tilted based on detection information obtained by the sheet inclination detecting unit. Registration device.   4. An image forming apparatus, wherein the registration device according to claim 1 is disposed upstream of an image forming unit.   4. An image reading apparatus, wherein the registration apparatus according to claim 1 is disposed upstream of an image reading unit.

Images